Windows 7: Resize system partition - weird problem!

OK, I know there is another topic like this but this is a little different. Now, I want to extend my system partition from 100 to 150 GB. I tried with paragon 2010 since I used it on my laptop without any problems but it didn't work. I was able to modify any partition on my "primary" HDD except C.
I tried with Computer Management utility but it didn't work.
There is something I didn't try. I want to break a partition in 2 parts, delete the 50gb one, so that the space becomes unallocated and then merge it with C:\.
Is this possible? As far as I know you can only merge 2 identically partitions primary + primary and logical + logical. The problem is that I never had 2 primary partitions on same HDD under same OS. The other question that comes in mind it's about the unallocated space that will result from splitting a partition in 2.
Considering the graphical representation in Computer Management, the data is been written on a partition from left to right. This means that between C:\ and the unallocated space there'll be partition D:\. Paragon handles this nicely by moving the data to the right before performing the other operations(I guess all other apps do this but since I never did this before and paragon is the only software I used for this....) but in this case it refuses to work. What's weird is that I used Paragon on my laptop to extend C:\ by taking 10 GB from D:\ and everything went fine. I didn't even had to create unallocated space or something. I don't understand what is the difference between my laptop HDD and my desktop HDD..
Any ideas?

LE: Never mind. I did it after all using Paragon. CM utility didn't let me tu extend system partition, don't know why.

Thank you, i also solved my problem using Paragon. I created a partition left from my system partition and then moved it with Paragon to the right. There i deleted it so i got unallocated space and then i just used extend partition in control panel.

!!! Important thing: UNALLOCATED SPACE must be to the right of system partition !!!